A silver halide color reversal photographic material has a narrow allowable light exposure range. Hence, in order to obtain good images using such a color photographic material, a very restricted suitable light exposure is required. That is, since the color images formed in the color reversal photographic material are viewed as final positive images, the gradation of the color photographic material is hard to select as compared with a color negative photographic material. Accordingly, it is required to use a color reversal photographic material having optimum sensitivity according to the purpose and the exposure conditions.
Also, for photographing specific scenes such as a sports photograph requiring a high shutter speed and a stage photograph lacking in the intensity of light for light exposure, a color photographic material having a high sensitivity is required but color reversal photographic materials having sufficient qualities for meeting the purpose of requiring the very high sensitivity as described above are few.
In such a circumstance, a high speed color reversal photographic material and sensitivity control by supplementing improper light exposure have strongly been desired.
For meeting these features, various development acceleration processes or sensitizing (or desensitizing) development processes have been proposed.
The process which has most generally been used is a process of prolonging the time for black-and-white development or a process of performing the development at a high temperature.
However, such a sensitizing (or desensitizing) process not always yields sufficient sensitizing processing aptitude to color reversal photographic materials.
That is,
(1) the time for the first development must be greatly prolonged as compared to that for standard processing for attaining sufficient sensitivity using a color reversal photographic material,
(2) in the case of a photographic material employing a construction having a high sensitive emulsion layer and a low sensitive emulsion layer, the gradation is changed by the sensitizing process since the development processing aptitude differs in both the layers,
(3) the attempt of increasing the sensitivity by prolonging the time for the first development causes a great reduction in color image density, and
(4) the color balance is deteriorated at the application of the sensitizing process due to the difference in development processing aptitudes among the red-sensitive emulsion layer, the green-sensitive emulsion layer, and the blue-sensitive emulsion layer.
Also, a process of using a development accelerator for obtaining high sensitivity is known. However, since as the development accelerators, cationic surface active agents, cationic dyes, neutral salts, polyalkylene oxides, organic amines, etc., described in L. F. A. Mason, Photographic Processing Chemistry, pages 41-44 (1966) (published by Focal Press, London & New York) are used, when these compounds are added to black-and-white developers, they show such strong tendencies that the development accelerating faculty becomes insufficient, the formation of fog is increased, and the maximum density of the reversal color images is lowered. Thus, the above described process is unsuitable for practical use.
For overcoming these difficulties, a process of using a black-and-white developer containing a thioether compound is proposed (Japanese Patent Application (OPI) No. 63530/82 (the term "OPI" as used herein refers to a "published unexamined Japanese patent application")). However, when the sensitizing degree is changed by changing the developing time or developing temperature in the foregoing process, the progress of development for a blue-sensitive emulsion layer, a green-sensitive emulsion layer, and a red-sensitive emulsion layer of a color reversal photographic material becomes irregular such that the color balance is lost.
For further overcoming the foregoing difficulty, there is proposed a process of using two balck-and-white developer baths (Japanese Patent Application (OPI) No. 81644/84). However, although a good performance can be obtained in the process, since the black-and-white development is composed of two steps in the process, the managements of processing liquids and processing conditions are complicated and very delicate, whereby it is difficult to maintain a constant photographic performance.
On the other hand, as an effective process for overcoming the above described difficulties in the sensitizing development, a process of restraining the formation of development fog in black-and-white development is known. For example, halogen compounds such as bromides, iodides, etc., are widely known for this purpose and are widely used for black-and-white developers. However, in the case of performing the sensitizing development, the fog restraining power by this process is insufficient and the desired purpose cannot be obtained.
Also, 1-phenyl-5-mercaptotetrazole, 4-phenyl-2-mercaptothiazole, 2-mercaptobenzoxazole, 2-mercaptobenzothiazole and 1,2-naphthyl-5-mercaptotetrazole described in U.S. Pat. No. 2,725,290 have an effect for preventing the upper emulsion layer(s) of a multilayer color photographic material from being excessively developed in the case of performing a high temperature black-and-white development process. However, since these compounds have a very high development restraining effect, the use of a small amount of the compound restrains the development of the upper emulsion layer(s). Accordingly, if a large amount of the compound is used for restraining the development or the formation of fog for the lower emulsion layer(s), the development for the upper emulsion layer(s) are excessively restrained such that the color balance is lost.
Furthermore, as compounds which have a weaker action than the foregoing development inhibitors (or anti-foggants), 5-methylbenzotriazole and 6-nitrobenzimidazole are known and described in the above described L. F. A. Mason, Photographic Processing Chemistry, pages 39-41 (1966). However, these compounds show a low antifogging effect for the lower emulsion layer(s) at black-and-white development and if a large amount of the compound is used, the compound shows a strong development inhibiting action for the lower emulsion layer(s) so as to reduce the sensitivity.
As described above, in the case of sensitizing processing or quick processing multilayer color reversal photographic materials, it is necessary to balance the antifogging effect for each emulsion layer at black-and-white development but it is very difficult to restrain the formation of fog at black-and-white development without reducing the sensitivity of the lowermost emulsion layer while reducing or removing the influence of the uppermost emulsion layer on the development.
Therefore, the development of a technique capable of solving the above described problems in conventional techniques and desirably controlling the extent of sensitization without showing any bad influences at standard processing has been desired.